Conventional attic fans, of the type which exhaust air through the ceiling of a house or building interior into the attic, have a flat box-like frame or housing having a large central opening which has an upwardly curved rim or flange therearound. The blades, usually four in number, are connected to a rotating shaft below a cast hub which is supported by rods, usually three or four in number, which depend from the housing around the central opening and are inwardly bent above the opening to be connected to the hub at their inner ends. A pulley is carried by the blade shaft above the hub. An electric motor having its shaft disposed vertically is supported by the housing, and a drive belt is disposed around the motor pulley and the pulley on the blade shaft. This invention seeks to provide a more economical construction for attic fans, wherein the cast hub and the large pulley or sheave on the blade shaft may be eliminated.